[Winpcap-users] About the packets loss , what is the bottleneck ?

[Gianluca Varenni]

Q1: tough question to answer, as it depends on a number of factors. What is the average packet size? Are you just counting the packets, or dumping them to disk/DB/...? Do you see packet drops in the pcap_stats?
Q2: I will need to run some tests on this. Do you have some minimal sample code that shows the issue?
Q3: Yes, *if* the NIC (and NIC driver) are not dropping packets themselves. 

Did you disable any protocol bound to the NIC where you receive all these packets?

Have a nice day
GV




From: yulou liu 
Sent: Wednesday, August 25, 2010 11:08 AM
To: winpcap 
Subject: [Winpcap-users] About the packets loss , what is the bottleneck ?


I'm using winpcap to capture datas from FPGA board via 1G Ethernet connection(directly connected).
the FPGA is configed to send data at a special rate. With the fpga sending  rate increases,especially above 500Mbps, it sometimes loss packets. 

Q1:  Is it possible to totally avoid packets loss by optimism the code?  I want to collect datas at speed 614Mbps without packet loss (collecting all datas 

last about 1 minutes). My workstations features with 2 Xeon CPU (each has 4core), DDR3 SDRAM, 1 G onboard  netcard.  Which part is the most probably bottleneck ?

Q2: As a test ,  I found the pcap_next_ex() can't get any packets  when the user buffer is set over 64 MB,  what does it happen ?

Q3: if the Kernel buffer's size is 16MB , then the first 16Mb packets from fpga won't be lost,  so ,  if I set the kernel buffer as 128MB ,  then at least 

the first coming 128MB data from FPGA won't be lost either ?  but I found When I set the kernel buffer bigger than 100 MB, the packets drops is getting 

worse.  


Thanks a lot!




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